TWI453078B - A five axis flank milling system for machining curved surface and a toolpath planning method thereof - Google Patents

Description

Five-axis surface side milling processing system and path planning method thereof

One aspect of the present invention is to provide a five-axis curved side milling system and a path planning method thereof. More specifically, the path planning method of the present invention is a reciprocating path planning method and multipath type proposed by the present invention. Path planning to reduce errors in side milling.

The five-axis machining process is suitable for cutting and forming complex surfaces, and has been widely used in the automotive, aerospace, energy and mold industries. Compared to the traditional three-axis machining, the five-axis machining tool has a higher degree of freedom and provides better molding capability. It can be divided into two types: end milling and side milling. The end milling process uses the cutting edge of the cutting edge to remove the material, while the side milling is the cutting edge through the shank part. In contrast, five-axis side milling is more efficient due to the large area of the material contacting the tool. On the other hand, it is difficult to control the surface error after processing, and the complexity of path planning is also high, and there is a lack of supported computer-aided manufacturing functions.

Among them, the side milling processing system is mainly for the Ruled Surface. If the surface is a expandable surface, the tool is generated by moving the tool along the ruled ruled line (Ruling) on the ruled surface. The situation of the error will improve. If the surface is Twist, there must be an error. The above errors can be divided into two types: overcutting error and letting error. The overcutting error is defined as the material that the workpiece should not be cut, but it is cut by the tool. The cutting error is the material that the workpiece should be cut off, but the tool is not cut.

Among them, most of the conventional techniques limit the two ends of the tool position to the boundary curve, so the obtained cutting error value is also limited by the tool position. To this end, several path planning tools have been developed in the prior art, which divide the machining path into a plurality of units, and respectively calculate the position of the tool in the unit to achieve the best error value, and then connect a plurality of mutual tool positions. To optimize the processing to find the minimum error value. However, the mathematical principle proves that after serializing the results of a plurality of single points optimization, the global error value cannot be improved. In view of this, the Republic of China Patent Application No. 96147909 discloses a surface cutting path planning method based on a global optimization method. The patent application proposes a relatively five-axis curved side milling method, which can automatically calculate the corresponding machining tool path while minimizing the overall cutting error of the curved surface, thereby providing a relatively flexible curved surface machining path planning method and accurate The error control mechanism.

In the past, the conventional five-axis machining process was well-suited for use in a general-purpose milling process such as an automobile engine. However, in today's fields where aerospace, military or large-scale transportation are extremely demanding in terms of efficiency and precision, the accuracy of the path planning method of the conventional five-axis machining process cannot meet the requirements. In view of this, how to develop a system and path planning method that can improve the accuracy of the conventional five-axis side milling process, it is necessary to think about the relevant industry, and to be the goal and direction of breakthrough.

In view of this, in order to further reduce the error of the conventional five-axis surface milling system. One aspect of the present invention is to provide a five-axis curved side milling system for generating a tool path for a tool to remove material of a workpiece along the tool path, the system comprising an interface module, an operation Module, a processing module and a control module.

The interface module is used to capture a design surface and a user command from a user. The machining module is equipped with a cutter for removing the material of the workpiece. The control module is coupled to the computing module and the processing module for controlling the processing module according to the tool path to enable the tool to machine the workpiece. The computing module is coupled to the interface module for generating a tool path based on the design surface and user commands. It should be noted that, in the present invention, the tool path includes a first tool position, a second tool position, and a third tool position, and the first tool position, the second tool position, and the third tool position are respectively Corresponding to the first time, the second time, and the third time, the first time is earlier than the second time, the second time is earlier than the third time, and the first tool position, the second tool position, and the third tool position are the same The end systems are respectively at a first coordinate, a second coordinate and a third coordinate, and the absolute distance between the first coordinate and the second coordinate is greater than the absolute distance between the first coordinate and the third coordinate.

However, the tool path of the present invention is not limited to the above description. In practical applications, the tool path includes a first sub-path and a second sub-path. The first sub-path is based on the user command and the design surface. The first indicator is designed, the first sub-path has a first error value, and the second sub-path is designed according to a user instruction and a design surface by a second indicator, and the second sub-path has a first The two error values, the first indicator and the second indicator are corresponding to the user instruction, and the order of the first sub-path and the second sub-path is independent of the sum of the first error value and the second error value.

Furthermore, the first sub-path in the tool path is used to remove material having a first volume from the workpiece, and the second sub-path is used to remove material having a second volume from the workpiece, the first indicator and The second indicator is corresponding to the user instruction, and the order of the first sub-path and the second sub-path is independent of the sum of the first volume and the second volume.

In addition, another aspect of the present invention also provides a path planning method for a five-axis curved side milling system for generating a tool path for a tool to remove a workpiece material along a tool path, including Step S11 to step S13. Step S11 is to prepare a design surface, step S12 is to prepare a user command, and step S13 is to generate a tool path according to the design surface and the user instruction, and the method is characterized in that the tool path includes a first tool position, a first The second tool position and the third tool position, the first tool position, the second tool position, and the third tool position respectively correspond to the first time, the second time, and the third time, and the first time is earlier than the second time, The second moment is earlier than the third moment, and the same end of the first tool position, the second tool position and the third tool position are respectively at a first coordinate, a second coordinate and a third coordinate, the first coordinate and the first coordinate The absolute distance between the two coordinates is greater than the absolute distance between the first coordinate and the third coordinate.

Furthermore, another aspect of the present invention also provides a path planning method for a five-axis curved side milling system, which includes steps S21 to S24. Steps S21 and S22 are similar to steps S11 and S12 described above, respectively, and thus are not described again. Step S23 is to design a first sub-path with a first index according to the user instruction and the design surface, and the first sub-path has a first error value. Step S24 is to design a second sub-path with a second index according to the user instruction and the design surface, and the second sub-path has a second error value. The first indicator and the second indicator are corresponding to the user instruction, and the order of the first sub-path and the second sub-path is independent of the sum of the first error value and the second error value.

In addition, the first sub-path and the second sub-path are also respectively used to remove the material having the first volume and the second volume from the workpiece, and the order of the first sub-path and the second sub-path is independent of The sum of the first volume and the second volume.

In summary, the present invention discloses several five-axis surface side milling processing systems, and a path planning method including a reciprocating path planning method M1 and a multi-path path planning method M2. When the reciprocating path planning method M1 is applied, the tool is not limited by the one-way advancement. Instead, through a smart algorithm, if a cutting error can be reduced in a certain local area, the tool can move in the opposite direction and resume the forward motion outside the area. Make full use of the freedom of tool movement to produce a machining surface with less cutting error. The multi-path path planning method M2 performs progressive multi-tool path planning on the same design surface by separately different indexes, so as to process the same design surface to minimize various errors. effect.

Before the present invention is further described, it is to be understood that all of the technical and scientific terms used in the specification have the same meaning as commonly understood by those skilled in the art. In addition, the presently described subject matter is only one of the many example methods of the present invention, and any method or means similar or equivalent to the methods and apparatus described herein may be used in the actual use of the present invention. For it. Furthermore, one or more of the numbers mentioned in the specification include the number itself.

It should be understood that the word "this" in the specification is synonymous with the term "invention". Furthermore, the present disclosure discloses certain methods and processes for performing the disclosed functions, and is not limited to the order described in the specification. Except that the specification is explicitly excluded, the steps of the steps and the sequence of the processes are viewed by the user. Free adjustment. Furthermore, the ratios between the various elements in the drawings in the present specification have been adjusted to maintain the simplicity of the drawings, and therefore, the corresponding size and position of the respective elements in the drawing are as described in the specification. The shapes are for reference only, and the arrangement of the features such as the size, position, and shape of each component can be freely changed depending on the requirements of the user without departing from the inventive concept of the present invention. Further, since the properties of the respective elements of the present invention are considered to be similar to each other, the descriptions and reference numerals between the respective elements apply to each other.

The invention discloses a five-axis curved side milling system and a tool path planning method thereof. In order to keep the description concise, the term tool path referred to in this specification refers to the path of the tool consisting of a plurality of continuous tool positions (Cutter Location), and the term workpiece refers to the object being processed, and the term design surface is used. Refers to the curved surface that the workpiece is to be machined into. Furthermore, the five-axis curved side milling system and method thereof in this specification will be represented by "processing system" and "planning method" respectively.

The planning method of the present invention is directed to a user command for rooting user input and provides a tool path for a tool to remove material from a workpiece along the tool path. To achieve the above effects, the present invention proposes two different methods to reduce the error of the conventional five-axis side milling system. The two methods mentioned above are the reciprocating path planning method M1 and the multi-path path planning method M2.

Before the present invention is further described, the application background of the above-described reciprocating path planning method M1 will be described first. It should be noted that before the planning of the tool path, the coding of the tool path must first be defined to generate an initial path. Then, according to the initial path described above, various global optimization algorithms are matched, and global optimization processing is performed on the initial path to obtain a corresponding tool path.

The calculation of the initial path will largely determine the accuracy of the tool path. Please refer to FIG. 1. FIG. 1 is a schematic diagram showing an initial path and its representative matrix. As can be seen from the figure, the conventional initial path 9 is obtained by selecting one point on the two boundary curves 91 and 92 of the design surface 90, and connecting any two points on the two curves to obtain the initial position of each tool. An initial path 9 can be formed by combining the positions of a plurality of tools. However, this encoding method limits the ability of each tool position to rest only on the boundary curves 91, 92, so that the error of the conventional tool path 9 cannot be effectively reduced.

Accordingly, the present invention proposes a reciprocating path planning method M1 to solve the above problems. To be more specific, please refer to Figure 1, Figure 2, Figure 3A and Figure 3B. 2 is a flow chart depicting the reciprocating path planning method of the present invention, and FIG. 3A and FIG. 3B respectively depict two schematic diagrams of the initial path in the reciprocating path planning method in a specific embodiment of the present invention. . As can be seen from the figure, the reciprocating path planning method M1 includes step S11, step S12, and step S13.

Step S1 is to prepare a design surface. More specifically, step S11 refers to taking a three-dimensional surface from a source or using other means. Step S12 is to prepare a user instruction, and the user instruction includes an overcut error minimization instruction, a handoff error minimization instruction or a total error minimization instruction, etc., for adjusting the amount of the cut error and the amount of overcutting error. Other parameters for calculating the tool path, such as the number of tool positions, tool position density, tool running speed, etc.

Step S13 is to generate an initial path 9 in a specified manner according to the design surface and the user instruction. In order to clearly illustrate the differences between the present invention and the prior art. Referring again to FIG. 1, the initial path 9 is composed of a plurality of coordinate points distributed on the two boundary curves 91 and 92. In the conventional initial path 9, the various coordinate points on the two boundary curves 91, 92 on the curved surface 90 are designed. to And by to All must be sorted and paired from small to large, so that the tool can be planned on the premise that it can only advance.

Different from the prior art, when calculating the initial path 9 of the present invention, the revolutionary initiative will be released to limit the order of each coordinate point. More specifically, the coordinate point of this initial path 9 to And by to It is not limited to sorting and pairing from small to large. When performing the operation of the initial path of the present invention, or The situation has to be included in the calculation. More specifically, the i + 2 tool position will be between the ith tool position and the ith +1 tool position. Thereby, the initial path 9 not only has to proceed, but also has to be partially retreated. Accordingly, the present invention obtains a reverse error in a local region in a certain partial region of the initial path 9, and performs a reverse motion in the local region, and resumes the forward motion after performing the reverse motion described above to reduce the initial path 9. The amount of error.

In order to clearly express the relative relationship of the tool positions in the reciprocating path planning method M1, please refer to FIG. 3A and FIG. 3B. As can be seen from the figures, the initial path 9 includes a first tool position P1, a second tool position P2, a third tool position P3 and a fourth tool position P4. The first tool position P1, the second tool position P2, the third tool position P3, and the fourth tool position P4 correspond to the first time, the second time, the third time, and the fourth time, respectively.

The first moment is earlier than the second moment, the second moment is earlier than the third moment, and the third moment is earlier than the fourth moment. The junctions of the first tool position P1, the second tool position P2, and the third tool position P3 at the upper boundary curve 91 (or the first edge) respectively have a first coordinate C1, a second coordinate C2, and a The third coordinate C3, at the same time, the absolute distance D2 between the first coordinate C1 and the second coordinate C2 is greater than the absolute distance D1 between the first coordinate C1 and the third coordinate C3.

Wherein, the first coordinate C1, the second coordinate C2, and the third coordinate C3 are respectively defined as coordinates of the end of the first tool position P1, the second tool position P2, and the third tool position P3 in the same direction. .

After determining the coding of the tool position in the above manner, the global path planning or other path optimization method can be used according to the initial path 9 described above to obtain a tool path having a reciprocating movement pattern in accordance with one of the user goals. . When the tool path is calculated according to the initial path described above, the total cutting error of the curved surface, the energy consumption of the tool during machining, and the like are all included in the calculation of the tool path to encode according to the initial path 9 or the corresponding position. To produce a series of tool paths. More specifically, the calculation of the tool path can be converge to a set of near-global optimal solutions through the evolutionary calculation method after a certain number of iterations by using random numbers or using local optimization. The above-mentioned evolutionary calculation methods include, for example, a Genetic Algorithm, a Particle Swarm Optimization, an Ant Colony Optimization, or a Simulated Annealing. Analytical method.

In addition, the present invention further proposes a multipath path planning method M2 to further improve the performance of the processing system. This multipath path planning method M2 is used to generate a tool path 8 for a tool to remove material of a workpiece along the tool path 8.

The tool path 8 is ordered and integrated by at least a first sub-path 81 and a second sub-path 82. At the same time, the tool path 8 has a total error value and a total processing amount. Referring to FIG. 4A to FIG. 4C, FIG. 4A is a schematic diagram showing a first sub-path of an embodiment of the present invention. 4B is a schematic diagram showing a second sub-path of an embodiment of the present invention, and FIG. 4C is a schematic diagram showing a tool path of an embodiment of the present invention.

More specifically, this multi-path path planning method M2 uses a different index to plan multi-path sub-paths in a progressive manner to form a complete tool path to repeat the same target surface and design surface 90 to minimize The effect of the error. It should be noted that each sub-path is calculated according to a corresponding index. The multi-path sub-path includes the first sub-path 81 and the second sub-path 82, respectively, which represent respective paths in which the tool mills the workpiece during repeated milling. In short, by performing milling on the same design surface 90 of the workpiece with the aim of minimizing the overcut error and minimizing the cutting error, the overcut error and the tangent error of the workpiece are minimized to a certain extent.

Furthermore, referring to FIG. 5, FIG. 5 is a flow chart showing a multipath planning method according to an embodiment of the present invention. As can be seen from the figure, the multipath path planning method M2 of the present invention includes steps S21 to S24. Steps S21 and S22 correspond to steps S11 and S12 of the above-described reciprocating tool path, and therefore will not be described again.

Step S23 is to design a first sub-path 81 according to the user instruction and the design surface 90 with a first index. The first sub-path 81 has a first error value. Step S24 is to design a second sub-path 82 according to the user instruction and the design surface 90 with a second index, and the second sub-path 82 has a second error value. In addition, the first indicator and the second indicator in steps S23 and S24 correspond to the user instruction, respectively.

According to a specific embodiment, the first indicator and the second indicator are respectively a calculation mode of overcut minimization and minimization. The first sub-path 81 described above refers to the calculation of the obtained plurality of tool positions by the calculation method of the overcut minimization, and the second sub-path 82 refers to the calculation method by minimizing the cut. The arrangement of multiple tool positions. In the tool path where the overcut error is minimized and the cut error is minimized, the overcut error or the cut error is prioritized respectively. By machining the cutting path that minimizes the cutting error and the cutting path that minimizes the overcutting error, the error of the workpiece in overcutting and cutting can be greatly reduced.

Accordingly, although the reference planes of the first sub-path 81 and the second sub-path 82 are both the same design curved surface 90, the first sub-path 81 and the second sub-path 82 are slightly different according to different calculation methods. difference.

Furthermore, the first sub-path 81 and the second sub-path 82 respectively remove the material having a first volume and a second volume from the workpiece, and respectively have a first error value and a second difference. In addition, the order of the first sub-path 81 and the second sub-path 82 is independent of the sum of the first volume and the second volume, or the sum of the first error value and the second error value. More specifically, the total error value and total cutting amount of the tool path will not be affected by the first and last order of the first sub-path 81 and the second sub-path 82.

It should be noted that the conventional technique also uses a method of rough milling and post-finishing to perform multiple milling of the workpiece, which has the advantages of reducing the wear of the expensive cutter or increasing the overall machining speed. However, the principle of the first coarse and fine finishing method is to use a milling cutter to machine a plane to mill a surface at a faster speed or a lower working distance, and reserve a certain thickness of material for subsequent precision. Milling. The biggest difference between the present invention and the prior art described above is that the reference surface or the design surface of the first sub-path and the second sub-path are the same when the path planning is performed in the present invention.

In addition, the present invention also discloses a five-axis curved side milling system corresponding to the reciprocating path planning method M1 and the multi-path path planning method M2 for generating a tool path for a tool along the tool path. Remove the material of a workpiece. Referring to Figure 6, Figure 6 depicts a functional block diagram of one embodiment of the present invention. The processing system 1 includes an interface module 10, a computing module 20, a processing module 30, and a control module 40.

The interface module 10 is used to capture a design surface and a user command from a user. The design surface and the user command have been described above, and therefore will not be described again. The computing module 20 is coupled to the interface module 10 for operating the reciprocating path planning method M1 and the multipath path planning method M2. The control module 40 is coupled to the computing module 20 and the processing module 30 for controlling the processing module 30 according to the tool path to cause the tool to machine the workpiece. In practical applications, the above processing system 1 refers to a five-axis machining tool machine connected to a computer.

Briefly, the path planning method of the present invention includes a reciprocating path planning method M1 and a multi-path path planning method M2. When applying the reciprocating path planning method M1, the tool path will actively exclude the one-way advancement limit during calculation so that it can perform the reverse movement of the local area to produce a machining surface with a smaller cutting error. The multi-path path planning method M2, by separately planning multiple tool paths for the same design surface for different indicators, is to process the same design surface to minimize the effects of various errors.

The features and spirit of the present invention will be more apparent from the detailed description of the preferred embodiments. On the contrary, the intention is to cover various modifications, and the equivalents are within the scope of the scope of the invention as claimed. Therefore, the scope of the patented scope of the invention should be construed in the broadest

1. . . Processing system

8. . . Tool path

9. . . Initial path

10. . . Interface module

20. . . Computing module

30. . . Processing module

40. . . Control module

81. . . First subpath

82. . . Second subpath

90. . . Design surface

91, 92. . . Boundary curve

M1. . . Reciprocating path planning

M2. . . Multipath path planning

P1. . . First tool position

C1. . . First standard

P2. . . Second tool position

C2. . . Second coordinate

P3. . . Third tool position

C3. . . Third coordinate

P4. . . Fourth tool position

D1, D2. . . Absolute distance

S11~S13, S21~S24. . . Process step

Figure 1 depicts a schematic diagram of an initial path and its representative matrix.

Figure 2 is a flow chart showing the reciprocating path planning method of the path planning method of the present invention.

Figure 3A is a schematic diagram showing the initial path in the reciprocating path planning method in one embodiment of the path planning method of the present invention.

Figure 3B is another schematic diagram showing the initial path in the reciprocating path planning method in one embodiment of the path planning method of the present invention.

Figure 4A is a schematic diagram showing a first sub-path of a specific embodiment of the path planning method of the present invention.

Figure 4B is a schematic diagram showing a second sub-path of a specific embodiment of the path planning method of the present invention.

Figure 4C is a schematic diagram showing the tool path of one embodiment of the path planning method of the present invention.

Figure 5 is a flow chart showing the multipath planning method of one embodiment of the path planning method of the present invention.

Figure 6 is a functional block diagram showing one embodiment of a five-axis curved side milling system of the present invention.

9. . . Initial path

90. . . Design surface

91, 92. . . Boundary curve

M1. . . Reciprocating path planning

C1. . . First standard

C2. . . Second coordinate

C3. . . Third coordinate

P1. . . First tool position

P2. . . Second tool position

P3. . . Third tool position

P4. . . Fourth tool position

D1, D2. . . Absolute distance

Claims (8)

A five-axis surface side milling system for generating a tool path for a tool to remove material of a workpiece along the tool path, comprising: an interface module for capturing a design surface from a user and a user And a computing module coupled to the interface module to generate the tool path according to the design surface and the user command; wherein the tool path includes a first tool position, a second tool position, and a first a third tool position, the first tool position, the second tool position, and the third tool position respectively corresponding to the first time, the second time, and the third time, the first time being earlier than the second At a moment, the second moment is earlier than the third moment, and the ends of the first tool position, the second tool position, and the corresponding direction of the third tool position are respectively at a first coordinate, a second coordinate, and a third coordinate, the absolute distance between the first coordinate and the second coordinate is greater than the absolute distance between the first coordinate and the third coordinate to move in the opposite direction. A five-axis surface side milling system for generating a tool path for a tool to remove material of a workpiece along the tool path, comprising: an interface module for capturing a design surface from a user and a user And a computing module coupled to the interface module to generate the tool path according to the design surface and the user command; wherein the tool path includes a first sub path and a second sub path, the a sub-path is calculated according to the user instruction and the design surface by a first index, the first sub-path having a first error value, the second sub-path is based on the user instruction and the design surface Calculated by a second index, the second sub-path has a second error value, the first indicator and the second indicator are corresponding to the user instruction, the first sub-path and the second sub- The order of the paths is independent of the sum of the first error value and the second error value. A five-axis surface side milling system for generating a tool path for a tool to remove material of a workpiece along the tool path, comprising: an interface module for capturing a design surface from a user and a user And a computing module coupled to the interface module to generate the tool path according to the design surface and the user command; wherein the tool path includes a first sub path and a second sub path, the a sub-path is designed according to the user instruction and the design surface by a first indicator, the first sub-path has a first error value, and the second sub-path is based on the user instruction and the design The curved surface is designed with a second index for removing material having a first volume from the workpiece, the second sub-path for removing a second volume from the workpiece The first indicator and the second indicator are corresponding to the user instruction, and the order of the first sub-path and the second sub-path is independent of the sum of the first volume and the second volume. The five-axis curved side milling system according to claim 1, wherein the processing module further comprises: a processing module including the tool for removing material of the workpiece; A control module is coupled to the computing module and the processing module for controlling the processing module according to the tool path to cause the tool to process the workpiece. A path planning method for a five-axis curved side milling system for generating a tool path for a tool to remove material of a workpiece along the tool path, the method comprising the following steps: Step S11: preparing a design surface; step S12 Preparing a user command; and step S13: generating the tool path according to the design surface and the user command; wherein the tool path includes a first tool position, a second tool position, and a third tool position, The first tool position, the second tool position, and the third tool position respectively correspond to the first time, the second time, and the third time, the first time being earlier than the second time, the first The second time is earlier than the third time, and the first tool position, the second tool position, and the third tool position are the same The end systems are respectively located at a first coordinate, a second coordinate and a third coordinate, and the absolute distance between the first coordinate and the second coordinate is greater than the absolute distance between the first coordinate and the third coordinate to move in the opposite direction . A path planning method for a five-axis curved side milling system for generating a tool path for a tool to remove material of a workpiece along the tool path, the tool path having a total error value, the method comprising the steps of: Step S21: preparing a design surface; step S22: preparing a user instruction; step S23: designing a first sub-path with a first index according to the user instruction and the design surface, the first sub-path having a a first error value; and step S24: designing a second sub-path with a second index according to the user instruction and the design surface, the second sub-path having a second error value; wherein the first indicator And the second indicator is corresponding to the user instruction, and the sequence of the first sub-path and the second sub-path is independent of the sum of the first error value and the second error value. A path planning method for a five-axis curved side milling system for generating a tool path for a tool to remove material of a workpiece along the tool path, the method comprising the following steps: Step S31: preparing a design surface; step S32 Preparing a user command; step S33: designing a first sub-path with a first index according to the user command and the design surface, the first sub-path for removing a first volume from the workpiece And a step S34: designing a second sub-path for removing a material having a second volume from the workpiece according to the user instruction and the design surface by a second index; The first indicator and the second indicator are corresponding to the user instruction, and the order of the first sub-path and the second sub-path is independent of the sum of the first volume and the second volume. The path planning method of claim 5, 6, or 7, wherein the user instruction includes an overcut error minimization command, a handoff error minimization command, or a total error value is minimized. instruction.